Below: Circling HD 69830 is a mammoth asteroid belt 25 times the size of the one in our solar system. If our asteroid belt were this dense, we would see it at night as a brilliant band across the sky. In 2006 three planets were discovered zipping around this sunlike star, each roughly the mass of Neptune. Frequent collisions between asteroids, such as the one depicted toward the right, send streams of dust into the belt, making it visible to the Spitzer Space Telescope.